Pipefitting square

ABSTRACT

A square for use in pipefitting having a plurality of markings disposed along edges thereof, each of the markings having numeral indicia associated therewith corresponding to an actual conventional pipe size. In particular, the numeral indicia correspond to conventional pipe sizes 2, 3, 4, 5, 6, 8, 10, 12, 14, 16, 18, 20, 24, and 30. One of the square tongue edges has markings with numerical degree indicia associated therewith, each of the markings including a line disposed at a numerically indicated angle α with respect to an edge of the body, all the lines intersecting the body edge at a common apex point. The square can be utilized for a plurality of pipefitting functions, and eliminates the need for complicated calculations, the square providing for readoff of the desired values.

BACKGROUND AND SUMMARY OF THE INVENTION

At present, pipefitters use a regular carpenter's square with linearmeasurements for assisting them in measuring conventional pipes andelbows for cutting, fitting and the like. After taking measurements witha conventional carpenter's square with linear measurements, thepipefitter must utilize trigonometric tables, drafting board layouts,and complex calculations in order to properly setup the pipes and elbowsfor cutting, fitting, and the like.

According to the present invention, a square is provided -- ofessentially the same overall size as a carpenter's square-for assistinga pipefitter in measuring pipes for cutting and fitting that eliminatesthe need for trigonometric tables, drafting board work, and thecomplicated calculations that are inherent in present procedures. Thesquare according to the present invention has numeral indicia thereoncorresponding to actual conventional pipe sizes rather than the abstract(for the purposes of pipifitting) linear measurement quantity providedon present squares. When utilizing the square according to the presentinvention, a pipefitter can directly readoff on the square the pipe sizehe is dealing with, no extraneous linear measurements being provided.According to another aspect of the present invention, numerical degreeindicia are disposed along one edge of the square and are associatedwith an "apex" point on an opposed inside edge of the square, to allowone to accurately draw and solve angles. By utilizing the squareaccording to the present invention, a pipefitter can accurately draw andsolve angles, find actual take-offs or center radii of long 90° elbows,find ordinates for saddle ons, find ordinates of mitered pipe, quarterthe outside circumference of pipe, find the outside center of pipe, andmark an elbow to cut it on its proper axis -- as well as many otherrelated functions -- without the need to resort to trigonometric tables,drafting board work, and complicated calculations.

The square according to the present invention -- as is true forconventional squares -- comprises a tongue and a body extendingperpendicular to the tongue, the tongue and body each having inside andoutside edges intersecting each other at inside and outside heelsrespectively, and each having a face surface and a back surface.Distinct from the squares of the prior art, according to the presentinvention a plurality of markings are disposed on at least one edge ofthe square, each of the markings having numeral indicia associatedtherewith corresponding to an actual conventional pipe size. Accordingto the present invention, pipes having the following conventional sizesmay readily be worked with: 2, 3, 4, 5, 6, 8, 10, 12, 14, 16, 18, 20,24, and 30. Markings disposed along one of the square edges may comprisemarkings that are spaced a distance from a reference equal to the actualoutside radius for the conventional numeral indicated pipe, thereference comprising a reference line indicated "outside center" and/orthe square inside heel. This allows the square to be used as a centerfinder and for quartering pipe. Other markings may be disposed along anedge that are spaced a distance l.5 PS from a given reference, whereinPS is the pipe size numeral indicia corresponding with the marking, thereference comprising the outside heel and/or a reference line, andallowing the pipe to be used for finding the actual take-off or centerradius of a long 90° elbow. Another edge may have markings that arespaced therealong from a reference corresponding to the formula IRP × βwherein IRP is the actual inside radius for a conventional particularpipe corresponding to the numeral indicia, and wherein β is the angleformed by division of a circumference into a number of divisions q sothat β = 360°/q, such markings being used for finding ordinates forsaddle ons. Additionally, one or more edges may have markings that arespaced therealong from a reference corresponding to the formula ORP × βwherein ORP is the actual outside radius for a conventional particularpipe corresponding to the numeral indicia, such markings being used forfinding ordinates for mitered pipe, and for finding ordinates for saddleons. Another set of markings may be provided along one edge, aparticular numeral indicia having three sets of markings correspondingthereto, for marking an elbow for cutting on its proper axis.

According to another aspect of the present invention, for drawing andsolving angles, one of the square tongue face edges has markings withnumerical degree indicia associated therewith, each of the markingscomprising a line disposed at a numerically indicated angle α withrespect to an edge of the body face, all the lines intersecting the bodyface edge at a common APEX point, each of the lines being located thedistance DP from a square heel wherein DP = DA × tan α, DA being thedistance the common APEX point is spaced along the body edge from thesame square heel from which the distance DP is measured.

It is the primary object of the present invention to provide a squarefor use with pipefitting that allows a pipefitter to cut and fitconventional pipe and elbows without resort to trigonometriccalculations, drafting board work, complex calculations, and the like.This and other objects of the invention will become clear from aninspection of the detailed description of the invention, and from theappended claims.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a plan view of the face of the square according to the presentinvention;

FIG. 2 is a plan view of the back of the square of FIG. 1; and

FIGS. 3-5 are schematic views of the square according to the presentinvention in use to perform several different tasks related topipefitting.

DETAILED DESCRIPTION OF THE INVENTION

The invention relates to a square -- in the same general form as aconventional carpenter's square -- having indicia formed on variousedges thereof so that the square may be utilized for performing a widevariety of tasks related to pipefitting without requiring the use ofdetailed calculations as is necessary in the prior art. In particular,according to the present invention, a square having actual pipe sizeindicia thereon is provided that allows one to accurately draw and solveangles, find actual take-offs or center radii of long 90° elbows, findordinates for saddle ons, find ordinates of mitered pipe, quarter theoutside circumference of pipe, find the outside center of a pipe, andfor marking an elbow to cut it on its proper axis, as well as many otherrelated functions.

The square according to the present invention is shown in plan view inFIGS. 1 and 2, FIG. 2 being the reverse side of FIG. 1 and vice-versa.The square has two flat planar surfaces thereof, the face A, and theback B, a tongue E (the relatively short and narrow arm of the square),a body F (the relatively long and wide arm of the square), an insideheel C (the inside intersection of the tongue E and the body F), and anoutside heel D (the outside intersection of the tongue E and the bodyF). The tongue E has a face inside edge G, a face outside edge H, a backinside edge K, and a back outside edge L; the body F has a face insideedge I, a face outside edge J, a back inside edge M, and a back outsideedge N. Each of the edges G-N has indicia markings formed thereon foruse in a wide variety of functions related to pipe fitting, and theparticular indicia markings that are utilized are dependent upon theparticular tasks one wishes to accomplish. The indicia markings havenumerals associated therewith, and with the exception of the anglesolving markings (P) on the face tongue inside edge, all of the numeralmarkings correspond to conventional pipe sizes. While of course thevariety of pipes with which the square according to the invention may beutilized may be varied depending upon the lengths of the members E, F,it is contemplated that according to the present invention the squaremay be utilized with conventional pipes 2, 3, 4, 5, 6, 8, 10, 12, 14,16, 18, 20, 24 and 30 for performing a wide variety of functions withrespect thereto. While the indicia markings on the square will behereinafter described with respect to particular edges, it is noted thatfor some of the markings disposition on other edges is possible withinthe scope of the invention, some of the indicia as illustrated in thedrawings merely being provided at the particular locations illustratedin order to save space and/or to provide completely clear markings. Inthis regard also, with a particular set of markings having the samenumeral repeated in that set, the markings for the different indicia areof different lengths so that it is easy to discern by a glance whichnumeral is with which set, although other indicia besides relativemarking line lengths could be utilized to distinguish between the setnumerals (i.e., colors).

The markings P on edge G are utilized to draw and solve angles, and asillustrated in the drawings, these markings can be used to accuratelydraw and solve angles from 30° to 90°. Each of the markings P comprisesa line disposed at its indicated angle with respect to the edge I at apoint on edge I marked "APEX" (see FIG. 1). A line extending through amarking line P will intersect edge I at a given angle α, and that angleis then indicated by a numeral above its respective marking line P. Forinstance, the angle α as shown in FIG. 1 is an angle of 39°, a lineextending from the "APEX" marking on edge I making an angle of 39° withrespect to edge I being coextensive with the particular marking P. Thedistance of each marking P from the heel C depends upon the distance the"APEX" mark is from the heel C along edge I, and in actual use for therelationships shown in FIG. 1 the "APEX" marking would be 14 inches fromC. The distance a marking P (DP) is from heel C, when the "APEX"distance from C is DA, is calculated according to the following formula,where α is the angle to be indicated.

    DP = DA × tan α;

for α = 30°, then, where DA = 14 inches, DP would be 8.0829 inches. Asshown in the drawings, the markings P may also be of varying length forease of recognition. For the markings actually illustrated, thoseindicating the halfdegrees are 0.125 inch, those indicating each wholedegree of a five are 0.25 inch, those indicating 2°, 3° and 4° of a fiveare 0.375 inch, 0.5 inch, and 0.625 inch respectively, and thoseindicating each 5° are 0.75 inch. Although it is preferred that themarkings P are disposed on the edge G, alternatively such markings couldbe disposed on the edge H and the "APEX" marking disposed on edge J, inwhich case the distance of each marking P from the heel D would bedetermined by the formula:

    (DP + WB) = (DA + WT) × tan α,

wherein WB is the width of the body F, and WT is the width of the tongueE.

The markings R on the edge H illustrated in FIG. 1 are primarily used tofind actual take-offs or center radii of a long 90° elbow. In FIG. 4athe markings R are shown schematically in use for the marking off of an8 inches long radius center at point 1 on line 2-3; lines 4-5 and 6-7represent the offset, and point 4 is the center of the cut ell. Themarkings R are related to markings formed on the edges N and L in amanner to be described hereinafter. The distance of the markings R fromthe heel D is determined according to the following formula:

    1.5(PS) + DO = DR, wherein

Ps is the pipe size (long radius 90° ell), DO is the distance of thezero mark on the edge H from heel D, and DR is the distance of the Rmarking corresponding to that pipe size. For the square illustrated, DO= 0.5 inch, thus for size 2 pipe, DR = 3.5 inches, for size 8, DR = 12.5inches, etc.

There preferably are two sets of markings, S, S', on the body faceinside edge I, each set of markings cooperating with an "Inside Center"marking. These markings S, S' are inside flat circumference divisionsfor conventional pipe, and the markings corresponding to each pipe sizenumeral for use in finding ordinates for saddle ons. The only reasonthat two sets of markings S, S' are provided instead of one is to makereading clear (so marking numerals do not interfere with each other),and to make best use of the available space. There are plurality ofdivision lines associated with each pipe numeral, preferably two suchdivision lines for 10 inch pipe and smaller, and four such divisionlines for 12 inch pipe and larger. Two such division lines for each pipenumeral make use of eight actual inside circumference divisions, whilefour such division lines for each pipe numeral make use of sixteenactual circumference division lines since a saddle on is the same on allquarters. The distance each marking S, S' is from the inside heel C iscalculated according to the following formula:

    (IRP × sin β ) + DIC = DS (or DS'), wherein

Irp is the actual inside radius of a particular pipe corresponding tothe pipe numeral indicated (i.e., IRP for a 10 inch pipe is 5.01 inches,for a 14 inch pipe is 13.25 inches, etc.), β is the angle formed byequal division of a circumference into a particular number of equaldivisions, and DIC is the distance the "Inside Center" mark for theparticular markings S, S' is from the inside heel C. β = 360°/q whereinq is a particular division of the circumference. When there are twodivision lines associated with each pipe numeral (i.e., for pipes 10inches or less), for the first division line (a 1/8 division; q = 8;360°/8 = 45°) β = 45°, and for the second division line (a 2/8 division;q = 4), β = 90°, or sin β = 1. Where there are four division linesassociated with each pipe numeral (i.e., for pipes 12 inches or more),for the first division line (a 1/16 division q = 16) β = 22.5°, for thesecond line (q = 8) β = 45°, for the third line (q = 16/3) β = 67.5°,for the fourth line (q = 4) β = 90°. Again, all the division linesassociated with a given pipe numeral can be of different lengths inorder to provide clear distinction therebetween for easy reading. Forthe structure actually illustrated in the drawings, the first "InsideCenter" mark is 0.5 inch from C, while the second "Inside Center" markis 15.625 inches from C; the markings S, S' first division lines for allof the pipe numerals illustrated in FIG. 1 have the following distancesfrom heel C: 2 -- 1.2307981 inches; 4 -- 1.9234124 inches; 5 -- 2.284392inches; 10 -- 4.0426211 inches; 16 -- 3,417935 inches; 18 -- 3,800615inches; 20 -- 4.183295 inches; 24 -- 4.948655 inches; 30 -- 6.096695inches; 3 -- 16.709706 inches; 6 -- 17.769311 inches; 12 -- 17.92108inches; 14 -- 18.160255 inches.

The markings T, T' disposed on the body face outside edge J are utilizedfor finding ordinates for mitered pipe, and have flat outsidecircumference divisions measured from "Outside Center" marks. In generalthey correspond to the marks S, S' except that they are for outsidecenters. Again, the only reason two sets of marks are provided insteadof one is for ready reading of the marks, and again a plurality ofdivision marks corresponding to each pipe numeral may be provided. Thedistance each mark T, T' is from the outside heel D along edge J iscalculated according to the following formula:

    (ORP × sin β) + DOC = DT (or DT'), wherein

Orp is the actual outside radius for a particular pipe corresponding tothe pipe numeral indicated (i.e., for a 5 inch pipe ORP = 2.7815 inches,for a 14 inch pipe ORP = 7 inches, etc.), β is the angle formed bydivision of a circumference into the number of divisions provided (seediscussion with respect to β for markings S, S' since the same appliesfor markings T, T'), and DOC is the distance of the "Outside Center"mark for the particular markings T, T' from the outside heel D. For thesquare actually illustrated in FIG. 1, the first "Outside Center" markis 0.75 inch from D, and the second one is 16.375 inches from D, and themarkings T, T' first division lines for all of the pipe numeralsillustrated in FIG. 1 have the following distances from D: 4 --2.3409975 inches; 5 -- 2.7168264 inches; 18 -- 4.19412 inches; 20 --4.5768 inches; 24 -- 5.34216 inches; 30 -- 6.4902 inches; 3 -- 17.612442inches; 6 -- 18.717301 inches; 8 -- 19.424411 inches; and 14 -- 19.05376inches. The ORP numbers can be determined by the table given below.

The markings U on the tongue back inside edge K may be used as a centerfinder, or in conjunction with the marks W on the body back inside edgeM for quartering the actual outside circumference of a pipe. The squareis shown for use in quartering in FIG. 3 of the drawings for a 10 inchpipe. The distance each marking U or W from the inside heel C iscalculated according to the following formula:

    ORP = DU (or DW), wherein

Orp (as for the markings T, T') is the actual outside radius for aparticular pipe corresponding to the pipe numeral indicated. Thefollowing table indicates these measurements:

    ______________________________________                                        PIPE SIZE      ORP = [DU or DW]                                               ______________________________________                                        2              1.1875"                                                        3              1.75"                                                          4              2.25"                                                          5              2.7815"                                                        6              3.3125"                                                        8              4.3125"                                                        10             5.375"                                                         12             6.375"                                                         14             7.0"                                                           16             8.0"                                                           18             9.0"                                                           20             10.0"                                                          24             12.0"                                                          ______________________________________                                    

The markings Y that are also disposed on the edge M do not have a directcorrelation to the markings W, but rather are merely located on edge Msince there is space on this edge therefor. The markings Y are flatoutside circumference divisions measured from the "Outside Center" markprovided thereon, and thus they in reality correspond exactly to themarkings T, T', not being provided on the same edge as the markings T,T' only to provide easy reading of the marks. A mark T, T', or Y ispreferably provided for each and every pipe from size 2 all the way tosize 30, and marks Y will be provided for those sizes missed on edge J.The distance of each mark Y from heel C as illustrated in thearrangement of FIG. 2 is calculated according to the formula:

    DOC - (ORP × sin β) = DY,

however if the marks were rearranged so that the "Outside Center" markwere closer to heel C and the markings Y were spaced outwardlytherefrom, the same formula would be used as for markings T, T'.

The tongue back outside edge L has two sets of markings associatedtherewith, the markings V (which are indicated as shorter than themarkings V' to provide ready distinction therebetween) being used for anoutside radius finder for saddle ons, and each marking V being spaced apredetermined distance from the "Outside Radius Finder" mark on edge L.Each mark V is a distance corresponding to the actual outside radius ofthe pipe numeral indicated from the "Outside Radius Finder" mark. Thusthe markings V are spaced the same distance from the "Outside RadiusFinder" mark as the markings U, W are from the heel C. For the squareactually illustrated, the "Outside Radius Finder" mark is 15.75 inchesfrom heel D, therefore the distance of each mark V from heel D iscalculated according to the following formula:

    DORF - ORP = DV, wherein

Dorf is the distance of the Outside Radius Finder mark from heel D, andORP is noted in the above table with respect to markings U and W. Themarkings V are arranged so that they run in the opposite direction asthe markings U so that outside radii can be readily determined withoutthe necessity of manipulating the square in an awkward position.

The markings V' on edge L are spaced in the same manner as the markingsX on body back outside edge N, and these two sets of markings may beutilized to provide takeoffs for center radii of long radius 90° elbows.Markings V', X are shown for this use in FIG. 4b after marking of aradius center of particular length with the markings R, as describedabove with respect to FIG. 4a. It is noted that the pipe numeralsassociated with markings V' are "upside-down" with respect to themarkings V; this is so that the markings V' can be utilized with themarkings X. The markings V', X are both the same distance (for a givenpipe numeral) from the heel D along their respective edges L, N. For an8 inch pipe the center radius is 12 inches, and for a 6 inch pipe thecenter radius is 9 inches, thus the marks 8 and 6 are respectively 12inches and 9 inches along the edges L, N respectively from heel D. Thedistance DV' or DX is calculated according to the formula 1.5 PS = DV'or DX, wherein PS is the pipe size numeral [same relative positioning asmarkings R].

The markings X along edge N are relatively long to distinguish them fromthe marking sets Z, Z' along the edge N, the markings Z, Z' also beingof different length than each other. The markings X, Z, Z' are used inconjunction with each other, as illustrated in FIG. 5, to cut an elbowalong its proper axis, the marks Z being the inside arc of a long radius90° elbow and the marks Z' being the outside arc of a long radius 90°elbow, while as mentioned above the marks X are the center arc of a longradius 90° elbow. The marks Z, Z' are spaced from the heel D accordingto the following formulas:

    DX - ORP = DZ; DX + ORP = DZ', wherein

Orp is the actual outside radius for a particular pipe corresponding tothe pipe numeral indicated (and can be determined from the above tablein the U, W markings description section), and DX is the distance of themark X from heel D.

The square according to the present invention may be made to exactly thesame dimensions as conventional carpenter's squares (i.e., length ofedges H, L = 16 inches, length of edges J, N = 24 inches, the tonguewidth WT = 1.5 inches and the body width WT = 2 inches, and given suchlengths can be used with a wide variety of conventional pipes -- forsome functions for pipes up to size 30. The proper placement of all ofthe markings on the square means that many difficult calculations thatwere previously necessary in order to perform particular pipefittingfunctions are eliminated, and instead direct readoff is provided on thesquare. All of the markings on the square (with the exception of theangle markings) have indicia corresponding to actual pipe sizes ratherthan some abstract measurement quantity (i.e., inches or centimeters),and this results in the ready utilization of the square according to thepresent invention for a wide variety of pipefitting functions.

While the invention has been herein shown and described in what ispresently conceived to be the most practical and preferred embodimentthereof, it will be apparent to those of ordinary skill in the art thatmany modifications may be made thereof within the scope of theinvention, which scope is to be accorded the broadest interpretation ofthe appended claims so as to encompass all equivalent structures anddevices.

What is claimed is:
 1. A generally rigid square for use in fitting pipeof conventional size, said square comprising a tongue and a bodyextending perpendicular to said tongue, said tongue and body each havinginside and outside edges intersecting each other at inside and outsideheels respectively, and each having a face surface and a back surface,wherein the improvement comprisesa plurality of markings disposed on atleast one edge of said square, each of said markings having numericalindicia associated therewith corresponding to an actual conventionalpipe size, and said markings being provided along a line extending froma reference on said square each marking being spaced from the referencea distance equal to the actual outside radius for the conventionalnumeral-indicated pipe indicated thereby.
 2. A square recited in claim 1wherein the reference is a reference line and is indicated "OutsideCenter", and wherein at least one of the following numeral markings areprovided spaced the indicated distance from the reference line 2 --1.1875 inches; 3 -- 1.75 inches; 4 -- 2.25 inches; 5 -- 2.7815 inches; 6-- 3.3125 inches; 8 -- 4.3125 inches; 10 -- 5.375 inches; 12 -- 6.375inches; 14 -- 7.0 inches; 16 -- 8.0 inches; 18 -- 9.0 inches; 20 -- 10.0inches; 24 -- 12.0 inches.
 3. A square as recited in claim 1 wherein thereference is the square inside heel and wherein two sets of saidmarkings are provided, one set of markings being disposed along each ofsaid tongue back inside edge and body back inside edge.
 4. A square asrecited in claim 1 wherein one of said square tongue face edges hasmarkings with numerical degree indicia associated therewith, and whereineach of said markings comprises a line disposed at a numericallyindicated angle α with respect to an edge of said body face and all saidlines intersecting said body face edge at a common "APEX" point, each ofsaid marking lines being located a distance DP from a square heelwherein DR = DA × tan α, DA being the distance the common "APEX" pointis along said body edge from the same square heel from which thedistance DP is measured.
 5. A generally rigid square for use in fittingpipe of conventional size, said square comprising a tongue and a bodyextending perpendicular to said tongue, said tongue and body each havinginside and outside edges intersecting each other at inside and outsideheels respectively, and each having a face surface and a back surface,wherein the improvement comprisesa plurality of markings disposed on atleast one edge of said square, each of said markings have numeralindicia associated therewith corresponding to an actual conventionalpipe size, and comprising markings that are spaced a distance 1.5 PSfrom a reference on said square wherein PS is the pipe size numeralindicia corresponding with each marking.
 6. A square as recited in claim5 wherein said reference is said outside heel and wherein two sets ofsaid markings are provided, one set of markings being disposed alongeach of said tongue back outside edge and said body back outside edge.7. A square as recited in claim 6 further comprising another set ofmarkings spaced a distance 1.5 PS from a reference line on said square,and wherein said reference line and said other set of markings aredisposed along said tongue face outside edge.
 8. A generally rigidsquare for use in fitting pipe of conventional size, said squarecomprising a tongue and a body extending perpendicular to said tongue,said tongue and body having inside and outside edges intersecting eachother at inside and outside heels respectively, and each having a facesurface and a back surface, wherein the improvement comprisesa pluralityof markings disposed on at least one edge of said square, each of saidmarkings having numeral indicia associated therewith corresponding to anactual conventional pipe size, and comprising markings that are spacedalong the at least one edge from a reference on said squarecorresponding to the formula IRP × sin β wherein IRP is the actualinside radius for a conventional particular pipe corresponding to thenumeral indicia and wherein β is the angle formed by division of acircumference into a number of divisions q, so that β = 360°/q.
 9. Agenerally rigid square for use in fitting pipe of conventional size,said square comprising a tongue and a body extending perpendicular tosaid tongue, said tongue and body each having inside and outside edgesintersecting each other at inside and outside heels respectively, andeach having a face surface and a back surface, wherein the improvementcomprisesa plurality of markings disposed on at least one edge of saidsquare, each of said markings having numeral indicia associatedtherewith corresponding to an actual conventional pipe size, andcomprising markings that are spaced along the at least one edge from areference on said square corresponding to the formula ORP × sin βwherein ORP is the actual outside radius for a conventional particularpipe corresponding to the numeral indicia and wherein β is the angleformed by division of a circumference into a number of divisions q, sothat β = 360°/q.
 10. A square as recited in claim 9 wherein at least twodifferent division lines having the same numeral indicia are providedfor at least one numeral indicia, each line spaced a distance from areference on said square determined by the formula ORP × sin β, andwherein q has a different value corresponding to the different numeralindicia, at least one value of q being 4, and at least one other valueof q being
 8. 11. A square as recited in claim 10 wherein two differentreference lines are provided on said square with markings spacedaccording to the formula ORP × sin β therefrom, each reference linehaving different pipe numerals associated therewith.
 12. A generallyrigid square for use in fitting pipe of conventional size, said squarecomprising a tongue and a body extending perpendicular to said tongue,said tongue and body each having inside and outside edges intersectingeach other at inside and outside heels respectively, and each having aface surface and a back surface, wherein the improvement comprisesaplurality of markings disposed on at least one edge of said square, eachof said markings having numeral indicia associated therewithcorresponding to an actual conventional pipe size, and said markingscomprising three sets of markings having the same numeral indiciaassociated therewith, each marking set comprising lines of differentlength, and wherein the distance of each marking of one set of markingsX from a reference on said square is determined according to the formulaDX = 1.5 PS wherein PS is the pipe size numeral indicia correspondingwith that marking, and wherein the distance of each marking of the othermarking sets Z, Z' from said reference is determined according to theformulas DZ - DX - ORP and DZ' - DX + ORP, wherein ORP is the actualoutside radius for a conventional particular pipe corresponding to thenumeral indicia.
 13. A square for use in fitting pipe of conventionalsize, said square comprising a tongue and a body extending perpendicularto said tongue, said tongue and body each having inside and outsideedges intersecting each other at inside and outside heels respectively,and each having a face surface and a back surface,wherein one of saidsquare tongue face edges has markings with numerical degree indiciaassociated therewith, each of said markings comprising a line disposedat a numerically indicated angle α with respect to an edge of said bodyface, all said lines intersecting said body face edge at a common,"APEX", point, each of said lines being located a distance DP from asquare heel wherein DP = DA × tan ×, DA being the distance the common"APEX" point is spaced along said body edge from the same square heelfrom where the distance DP is measured, said square further comprising aplurality of markings disposed on each of the other edges of the square,each of said markings having numeral indicia associated therewithcorresponding to an actual conventional pipe size, said tongue backinside edge and said body back inside edge having markings disposedthereon spaced from said inside heel a distance equal to the actualoutside radius for the indicated conventional particular pipe numeral,said tongue face outside edge having a line with the indicia "OutsideCenter" disposed thereon and a plurality of markings being providedspaced along said tongue face outside edge a distance equal to theactual outside radius for the indicated conventional particular pipenumeral from said "Outside Center" line, said tongue back outside edgeand said body back outside edge each having markings disposed therealongspaced a distance 1.5 PS from said outside heel wherein PS is the pipesize numeral indicia corresponding to each marking, said tongue faceoutside edge having a reference line with indicia "O" disposed thereonand having markings disposed therealong spaced a distance 1.5 PS fromsaid "O" indicia, said body face inside edge having markings spaced adistance from a reference therealong according to the formula IRP × sinβ, wherein IRP is the actual inside radius for a pipe size numeralcorresponding to the marking, and wherein β is the angle formed bydivision of a circumference into a number of divisions q, so that β =360°/q, and said body face outside edge having at least one referenceline thereon with indicia "Outside Center", and having markings spaced adistance from said reference line therealong according to the formulaORP × sin β, wherein ORP is the actual outside radius for a pipe sizenumeral corresponding to the marking.